As a gas-barrier film laminate comprising a gas-barrier film for use for packaging materials, for example, heretofore known are one produced by laminating layers of transparent resin layer/oxide thin film layer/moisture-absorbing resin layer via an adhesive layer for the purpose of enhancing the water vapor-barrier property thereof (see Patent Document 1); one produced by laminating at least two resin layers and laminating an organic/inorganic hybrid layer formed according to a sol-gel process between the layers for the purpose of enhancing the heat resistance and the gas-barrier property thereof (see Patent Document 2), etc.
In case where gas-barrier films are laminated via an adhesive layer in the manner as above and when the adhesive layer is cured by heating, then various gases such as carbon dioxide are formed during curing reaction or owing to the later influence of moisture in the substrate or in air, whereby the laminate structure may be whitened owing to bubbling or foaming to occur between the laminated gas-barrier films, therefore causing a problem in point of the appearance thereof. When the bubbling or foaming is too much, then it may cause the reduction in the gas-barrier property and the reduction in the lamination strength.
In particular, in case where an isocyanate-based adhesive is used, a reaction gas such as carbon dioxide may be often generated with the curing reaction during curing, and in case where gas-barrier films are multi-laminated, there occurs a problem in that a large quantity of bubbles are generated.
In addition, in case where gas-barrier films are multi-laminated, there occurs another problem in that air remaining in the interface between the adhesive and the gas-barrier film may form bubbles to worsen the appearance of the laminate.
Regarding the problem, in Patent Document 3, the adhesive composition is specifically noted, and a film that has solved the problem of foaming whitening and bubbling contamination by removing the influence of moisture thereon is disclosed.
The film could improve the intended property mentioned above in some degree, but is still insufficient in point of the gas-barrier property and the lamination strength (interlayer adhesiveness) of the laminate, and it is desired to improve this.
[Patent Document 1] JP-A 2003-249349
[Patent Document 2] JP-A 2004-136466
[Patent Document 3] JP-A 2006-51751